Referring to FIG. 1, in a worldwide interoperability for microwave access (WiMAX) communication system, paging and idle mode operations of a mobile station (MS) involve the following functional entities: paging controllers (PCs), paging agents (PAs), paging groups (PGs), and location registers (LRs).
The PC decides the behavior of the MS in an idle mode in the network. The PC defines a parameter, PC ID, which indicates a 6-byte address of one PC functional entity. The PA is located at a base station (BS) for solving a problem about an interaction between the PC and paging related functional entities in the BS as defined in the Institute for Electrical and Electronics Engineers (IEEE) 802.16e. The PG should be large enough so that the MS is held in the same PG most of the time, and it should be small enough to reasonably distribute the paging load. A LR is a distributed database, each LR corresponds to one PC, and the LR contains MS information in the idle mode, which includes current PG ID, paging cycle (PAGING_CYCLE), paging offset (PAGING_OFFSET), latest reported BS ID, latest reported relay PC ID, and MS service flow information.
Referring to FIG. 2, in the WiMAX communication system, an existing paging process includes the following steps.
In Step 1, data from a home agent (HA) reaches an anchor foreign agent (FA) and a related data path function (DPF), and is buffered there.
In Step 2, the anchor DPF recognizes that a MS is in an idle mode and needs to be activated and the data needs to be transmitted to the MS. An anchor FA sends a MS information request (MS_Info_Request) message to an anchor PC/LR in order to obtain paging information of the MS and request paging for the MS.
In Step 3, the anchor PC/LR sends MS-related information to the anchor DPF through a MS information response (MS_Info_Response) message.
In Step 4, the anchor PC generates a paging announcement message and sends one or more paging announcement messages to other paging areas known by the anchor PC.
When the MS is in an idle mode, it sends a ranging request (RNG-REQ) message to a BS according to four different conditions, so as to trigger the PA to send a location update (LU) message. The RNG-REQ message sent to the BS by the MS includes an ID of the current anchor PC of the MS. When the MS moves in the idle mode, the anchor PC may be far away from the position where the LU is initiated currently. In this manner, it is necessary to redirect the anchor PC. This is one of the above four conditions for initiating a LU.
In the existing location updating process for the WiMAX communication system, after the PC receives a LU request message from the PA, it immediately returns a LU response message to the PA. If a relay PC exists, the PA sends the LU message to the relay PC first, and then the relay PC sends the message to the anchor PC. After receiving the LU request message, the anchor PC immediately sends the LU response message to the relay PC. Then, the relay PC sends the response message to the PA. After receiving the response message, the PA sends a LU acknowledgement message to the relay PC. Then, the relay PC sends the acknowledgement message to the anchor PC.
The RNG-REQ sent to the BS by the MS includes the ID of the current anchor PC of the MS: PC ID. When the MS moves in the idle mode, the anchor PC may be far away from the position where the LU is currently initiated. In this manner, it is necessary to redirect the anchor PC.
The process of redirecting an anchor PC by a MS is described below with reference to FIGS. 3 to 5.
In Step 1, the MS sends a RNG-REQ message to a serving BS (SBS, the BS where the PA is located). The RNG-REQ message includes a destination of the LU, as well as an ID of the current anchor PC of the MS.
Then, Step 2 is performed as follows.
1) The BS searches to determine whether it has valid security information or not, so as to verify the RNG-REQ message of the MS. The security information is an anchor authenticator ID, or an authentication key (AK), and AK context buffered in the MS. If the RNG-REQ message requests redirecting the anchor PC, it should further include a redirection address of the anchor PC, i.e. PC ID.
2) Once a relay PC receives a LU request message from the SBS, if the SBS owns the valid security information of the MS, it directly performs Step 5 below; otherwise, the relay PC forwards the LU request message to the anchor PC. The message includes a security information indication for notifying the anchor PC that the SBS does not reserve the security information. A primitive structure of the LU request message is shown in FIG. 4.
In Step 3, after receiving the LU request message, the anchor PC searches relevant information from a LR. If the anchor authenticator stores some security information, the anchor PC extracts the anchor authenticator ID of the MS and then sends an MS_Info_Request message to the anchor authenticator. A primitive structure of the MS_Info_Request message is shown in FIG. 5.
In Step 4, after receiving the MS_Info_Request message, the anchor authenticator generates the AK and AK context of the MS and then sends a MS_Info_Response message to the anchor PC. A primitive structure of the MS_Info_Response message is shown in FIG. 6.
In Step 5, an ASN where the anchor PC of the MS is located sends a LU response message to the relay PC. The LU response message includes MS ID, BS ID, assigned PG ID, anchor PC ID, PAGING_CYCLE, PAGING_OFFSET, MS data structure, and LU status. If a source address (i.e., the anchor PC) is assigned with a different anchor PC, the PC ID thereof is included in the LU response message. If an authentication indication included in the LU request message indicates that the SBS do not have the valid security information of the MS, the anchor authenticator ID is also included. If the LU request message requests relocating the anchor PC, the LU response message may include a response to the redirection request. A primitive structure of the LU response message is shown in FIG. 7.
In Step 6, an ASN where the relay PC is located forwards the LU response message to the BS (PA). The message includes new PG ID, PAGING_CYCLE, or PAGING_OFFSET, and may also include the following information: AK and AK context, and anchor authenticator ID.
If the BS does not obtain available AK and AK context directly after receiving the LU response message from the relay PC, the BS obtains the anchor authenticator ID and sends a context request message to an ASN where the anchor authenticator is located to request for an AK and uses the AK to verify the received RNG-REQ message. If the verification succeeds, the BS sends a ranging response message including HMAC/CMAC to the MS.
In Step 7, if the RNG-REQ message is successfully verified, the BS (PA) sends a LU acknowledgement message (including MS ID, BS ID, and result indication) to the relay PC to indicate that the LU from the MS has been authenticated and processed successfully. A primitive structure of the LU acknowledgement message is shown in FIG. 8.
The LU acknowledgement message sent to the anchor PC by the relay PC includes result indication, relay PC ID, new PG ID, and PAGING_CYCLE and PAGING_OFFSET assigned by the relay PC. After receiving the LU acknowledgement message, the anchor PC finally updates the MS location information in the LR.
In Step 2 of the above process of performing the LU by the MS, the BS sends the LU request message to the relay PC, and the relay PC determines that the current PC is far away from the original anchor PC and it is necessary to assign a new anchor PC, according to information (for example, PC ID and BS ID) included in the message. Therefore, the LU request message sent to the anchor PC by the relay PC includes an address of the new anchor PC assigned by the relay PC, i.e. an redirection address of the anchor PC (PCID). The anchor PC is optionally assigned by the relay PC, and alternatively, a new anchor PC may be assigned by the current anchor PC. If it is the relay PC that assigns the new anchor PC, the current anchor PC has the right to decide whether to accept or refuse to be the new anchor PC.
However, after the anchor PC is redirected, the FA does not know the address of the new anchor PC in the paging process. When Step 2 of the paging process in the WiMAX communication system in the prior art is performed, the anchor FA needs to send a MS_Info_Request message to the anchor PC/LR, so as to obtain paging information of the MS and request paging for the MS. However, since the FA does not know the address of the new anchor PC, the data cannot be transmitted to the new anchor PC from the FA and cannot be transmitted to the called MS accordingly. Thus, the paging process cannot be implemented.
Therefore, there is a need of an information management method, which enables the FA to obtain an address of a new anchor PC and thus perform information interaction with the PC, thereby implementing a paging process.